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Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_16 | Pages 40 - 40
17 Nov 2023
Kuder I Jones G Rock M van Arkel R
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Abstract

Objectives

Ultrasound speckle tracking is a safe and non-invasive diagnostic tool to measure soft tissue deformation and strain. In orthopaedics, it could have broad application to measure how injury or surgery affects muscle, tendon or ligament biomechanics. However, its application requires custom tuning of the speckle-tracking algorithm then validation against gold-standard reference data. Implementing an experiment to acquire these data takes months and is expensive, and therefore prohibits use for new applications. Here, we present an alternative optimisation approach that automatically finds suitable machine and algorithmic settings without requiring gold-standard reference data.

Methods

The optimisation routine consisted of two steps. First, convergence of the displacement field was tested to exclude the settings that would not track the underlying tissue motion (e.g. frame rates that were too low). Second, repeatability was maximised through a surrogate optimisation scheme. All settings that could influence the strain calculation were included, ranging from acquisition settings to post-processing smoothing and filtering settings, totalling >1,000,000 combinations of settings. The optimisation criterion minimised the normalised standard deviation between strain maps of repeat measures. The optimisation approach was validated for the medial collateral ligament (MCL) with quasi-static testing on porcine joints (n=3), and dynamic testing on a cadaveric human knee (n=1, female, aged 49). Porcine joints were fully dissected except for the MCL and loaded in a material-testing machine (0 to 3% strain at 0.2 Hz), which was captured using both ultrasound (>14 repeats per specimen) and optical digital image correlation (DIC). For the human cadaveric knee (undissected), 3 repeat ultrasound acquisitions were taken at 18 different anterior/posterior positions over the MCL while the knee was extended/flexed between 0° and 90° in a knee extension rig. Simultaneous optical tracking recorded the position of the ultrasound transducer, knee kinematics and the MCL attachments (which were digitised under direct visualisation post testing). Half of the data collected was used for optimisation of the speckle tracking algorithms for the porcine and human MCLs separately, with the remaining unseen data used as a validation test set.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_13 | Pages 66 - 66
7 Aug 2023
Holthof S Amis A Van Arkel R Rock M
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Abstract

Introduction

Mid-flexion instability may cause poor outcomes following TKA. Surgical technique, patient-specific factors, and implant design could all contribute to it, with modelling and fluoroscopy data suggesting the latter may be the root cause. However, current implants all pass the preclinical stability testing standards, making it difficult to understand the effects of implant design on instability. We hypothesized that a more physiological test, analysing functional stability across the range of knee flexion-extension, could delineate the effects of design, independent of surgical technique and patient-specific factors.

Methods

Using a SIMvitro-controlled six-degree-of-freedom robot, a dynamic stability test was developed, including continuous flexion and reporting data in a trans-epicondylar axis system. 3 femoral geometries were tested: gradually reducing radius, multi-radius and single-radius, with their respective tibial inserts. 710N of compression force (body weight) was applied to the implants as they were flexed from 0–140° with three levels of anterior/posterior (AP) tibial force applied (−90N,0N,90N).


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 299 - 299
1 Sep 2005
Fuchs B Inwards C Sim F Rock M
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Introduction and Aims: Multimodal treatment has dramatically improved the outcome of patients with Ewing’s sarcoma. However, little is known about treatment-related complications in patients who are long-term survivors.

Method: Forty-one patients with Ewing’s sarcoma treated at the authors’ institution between 1963 and 1980 and who survived by at least 20 years were included in this study. This patient group comprises 17 men and 24 women. The mean age at presentation was 16.8 (range five to 51) years. Three patients presented with metastatic disease. The location included 14 axial, and 27 appendicular lesions. All but nine patients had chemotherapy as part of their multimodality treatment.

Results: The overall follow-up averaged 297 (range 240–430) months. All except one patient were alive at final follow-up, the latter dying of radiotherapy-induced secondary malignancy after 33 years. Five patients survived, despite developing local recurrence or metastatic disease. Only 16 (39%) patients were free of any complication. These included metastases (12%), local recurrence (7%), secondary malignancies (7%), pathologic fractures (20%), and radiation (32%), and chemotherapy-associated morbidities (20%). The complication rate in this series of long-term survivors treated prior to 1980 is surprisingly high. Current treatment advances should result in improved long-term results.

Conclusion: Even when patients with Ewing’s sarcoma survive the primary cancer, only a minority of them remain without treatment-associated morbidities.